Preliminary Sizing of Concrete Beams
Member | Span/Depth Ratio | Max. Recommended Span |
---|---|---|
Rectangular Beam | 10 to 14 (cont. 20 to 26) | 8m (cont. 12m) |
Flanged Beam | 12 to 18 (cont. 18 to 21) | 10m (cont. 14m) |
Cantilever | 2 to 6 | 5m |
Band Beams | 18 to 20 | 12m |
The maximum spans listed here are not absolute limits. Longer spans are possible with every type, but
may not be economical. As a rule of thumb for estimates of thickness above the span on deflection ratio’s
should be multiplied by “maximum recommended span”/”actual span”)
The higher number are given for light loadings (about 1.5 kpa) and the lower numbers for heavy loadings
(about 10kpa)
*2010 Design Tips by Rowing Engineer
Preliminary Sizing of Concrete Slabs
Member | Span/Depth Ratio | Max. Recommended Span |
---|---|---|
One-way Simply Supported | 20 to 30 | 6m |
One-way Continuous | 28 to 34 | 7m |
Two-way Simply Supported | 24 to 34 | 6.5m |
Two-way Countinuous | 30 to 34 | 7.5m |
Cantilever | 6 to 11 | 3m |
Flat Slab | 23 to 28 | 7m |
The maximum spans listed here are not absolute limits. Longer spans are possible with every type, but
may not be economical. As a rule of thumb for estimates of thickness above the span on deflection ratio’s
should be multiplied by “maximum recommended span”/”actual span”)
The higher number are given for light loadings (about 1.5 kpa) and the lower numbers for heavy loadings
(about 10kpa)
*2010 Design Tips by Rowing Engineer
Preliminary Sizing of Steel Members
Element | Span/depth ratio | Maximum span |
---|---|---|
Purlins | 32 | 12m |
Roof beams (light dead loading) | 18-30 | 6-30m |
Floor I beams and joists | 18 | 18m |
Floor Plate girder | 41194 | 25m (80’) |
Floor Joist (steel only) | 17 | 6-9m (20-30’) |
Castellated UB’s* | 14-17 | 12-20m(40-70’) |
Transfer beams | 10 | 6-30m |
Trusses supporting floors | 10 | 6-30m |
Roof trusses (pitch>20) | 14-15 | 17m (55’) |
Space Frames | 15-30 | 100m (300’) |
Primary beams (supported by columns) | 41197 | 12m (40’) |
Secondary beams (supported by other beams) | 15-25 | 10m (33’) |
Portal frame leg | 35-40 | 60m (200’) |
Simple span rafter | 24 | 30m (100’) |
Simple span roof beam | 15 | 25m (80’) |
Con’t beam or joist | .85 * simple span value | |
Column SHS | H/D 20-35 | 2-8m |
*2010 Design Tips by Rowing Engineer
Engineering Related Quotes
These quotes are provided to inspire you, give you confidence and show you that engineering has no black
and white, just shades of grey.
“The road to success is always under construction”
Get it right….CIVIL ENGINEERS
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
- Douglas Adams
Aeroplanes are not designed by science, but by art in spite of some pretence and humbug to the contrary. I do not mean to suggest that engineering can do without science, on the contrary, it stands on scientific foundations, but there is a big gap between scientific research and the engineering product which has to be bridged by the art of the engineer.
- British Engineer to the Royal Aeronautical Society, 1922.
A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible
- Freeman Dyson
Read More..
Great Engineers
Engineers have always made a difference. They are the thinkers and innovators that shape our world. Find out here about some of the greatest engineers of all time.
Ove Arup (1895 - 1988)
Sir Ove Nyquist Arup is generally considered one of the foremost engineers of the twentieth century. Groundbreaking use of precast concrete, structural glue and computer analysis helped to make Arup's reputation, and that of his firm, Arup. The multi-disciplinary company provided engineering, architectural, and other services for the built environment.
Notible projects included the The Sydney Opera House, which Arup worked on from 1957 to 1973. Before his death Arup received a Knighthood from both the British and Danish monarchy along with a plethora of industry commendations.
Sir John Fleetwood Baker (1901-1985)
Sir John Fleetwood Baker was one of the first winners of the Institution's Gold Medal award. During the 1930’s Baker carried out tests on buildings which brought a revelation that led to Baker’s life work on the development of the plastic theory of design.
During the Second World War, Baker was appointed Scientific Adviser to the Ministry of Home Security, focussing on reducing the impact of bombing of buildings, especially industrial sites and factories. Read More..